In order to acquire an image causing a person to sense a stereoscopic effect and depth, there is a method of utilizing a difference between viewpoints of right and left eyes. This difference is a “binocular parallax” where object images viewed by right and left eyes are different from each other. A display apparatus has been developed which utilizes the binocular parallax, presents different images for the right and left eyes of an observer and thereby makes the observer sense a stereoscopic effect.
Among such display apparatuses, a configuration has been known which provides a display panel with pixels for displaying images for right and left eyes and causes optical means, such as a lenticular lens and a parallax barrier, to separate images corresponding to right and left eyes. The optical means is not limited to a static element, such as a fixed lens. Instead, an electrooptic element, such as a liquid crystal lens and a liquid crystal barrier, may be adopted. A configuration is also known which adopts optical means for separating light emitted from a light source such as a backlight for right and left eyes in a time division manner. The number of viewpoints may be selected in various manners from two viewpoints to multi-viewpoints in accordance with the application or usage circumstances of the observer. The two viewpoints have a limited stereoscopic visual field, which provides a stereoscopic effect. However, two viewpoints have an advantage providing high 3D (three-dimensional) resolution. On the other hand, the multi-viewpoints have lower 3D resolution but have an advantage of being capable of providing motion parallax and enlarging the stereoscopic visual field.
In order to correctly separate a prescribed image for the right and left eyes of the observer, it is important that the amount of positional deviation of optical means from a display panel is small. In other words, mounting accuracy (hereinafter referred to as relative positional accuracy between the display panel and the optical means) of the optical means with respect to the display panel is important. Deviation between positions of the display panel and the optical means causes a reverse view phenomenon, in which right and left images are replaced with each other depending on viewpoints, and a phenomenon in which the right and left images are mixed with each other. In these cases, the observer cannot recognize the stereoscopic image, or the region where the stereoscopic image can be recognized is narrowed. Accordingly, in the case of manufacturing a display apparatus for displaying an image that makes an observer sense a stereoscopic effect, it is important to manage relative positional accuracy between the display panel and the optical means.
In order to address these problems, various methods for evaluating mounting accuracy have been proposed. Typically, a method of reading relative positional accuracy between a display panel and optical means using a length measurement microscope or the like, and a method that detects light separated for right and left eyes by an optical property measurement apparatus, such as a conoscope system and a Fourier system, and that acquires a region where a stereoscopic image can be recognized have been known.
However, these evaluation methods require much preparation time and have a lot of operation procedures, and equipment required for evaluation is expensive. Accordingly, there is a problem in that adoption of these methods increases inspection cost.
Further, there is a method that preliminarily provides markers on a display panel and on optical means, detects the shapes and positions of the markers using an optical system and a sensor more inexpensive than the length measuring microscope and thereby detects relative positional accuracy between the optical means and the display panel. However, according to such a method, it is difficult to photograph the markers of the display panel and the optical means at the same focus. Further, there is another problem in that the positional deviation cannot be detected at an accuracy required according to tendency of increasing high definition in a display panel.
Thus, a method has been proposed that acquires a relative positional accuracy of a display panel and optical means without using expensive equipment by observing a prescribed test pattern.
For instance, in Japanese Patent Laid-Open No. 2007-65441, a method for deriving arrangement lens specifications that causes a display apparatus, such as an inspection target to display a group of parallel lines, matches color stripes observed via a lenticular lens array with a prescribed condition and thereby acquires an arrangement direction of the lenticular lens array arranged on the screen of the display apparatus for stereoscopic view.
FIG. 1 is a schematic diagram showing an example of an inspection image displayed on a display apparatus illustrated in Japanese Patent Laid-Open No. 2007-65441.
As shown in FIG. 1, in the art described in Japanese Patent Laid-Open No. 2007-65441, the display apparatus to be inspected displays a group of parallel lines including equidistant parallel lines. Here, the top left corner of the display screen is defined as O1. A horizontal direction with respect to the reference position O1 is defined as xp axis, and the vertical direction is defined as yp axis. The angle θ between each line in the parallel line group and yp axis is defined as “line group angle”. The separation m between adjacent lines is defined as “line group separation”. The distance dx at a position on the line nearest from reference position O1 and on xp axis from reference position O1 is defined as “horizontal reference position”. If angle θ of the parallel line group, line group separation m and horizontal reference position dx are adjusted so as to meet conditions in which, for instance, the angle of color stripes viewed via the lenticular lens array and the arrangement angle of the lenticular lens array match with each other, the arrangement lens specifications, such as a lens pitch and an arrangement angle of the lenticular lens array, can be acquired even though the arrangement base position of the lenticular lens is unknown.
Japanese Patent Laid-Open No. 2006-79097 has proposed a method for manufacturing a three-dimensional image display apparatus that performs arrangement and fixation so as to eliminate the positional deviation between an image panel and a three-dimensional image formation apparatus (optical means) while observing a displayed three-dimensional image.
FIG. 2 is a schematic diagram showing a principle of checking the lens mounting accuracy described in Japanese Patent Laid-Open No. 2006-79097.
As shown in FIG. 2, when light beams emitted from two pixel arrays are refracted by a lens such that the light beam from one pixel array reaches the right eye and the light beam from the other pixel array reaches the left eye, no light reaches the center of both eyes, and a black band appears at the center of a three-dimensional image. In a case where optical means (three-dimensional image forming apparatus), such as a lens, and two pixel arrays of the image panel are fixed without positional deviation, if an observer takes a look at a prescribed observation distance (or a prescribed focal length) from the center of the image panel, the black band appears at the center of the image panel in a vertical direction. In Japanese Patent Laid-Open No. 2006-79097, for instance, the three-dimensional image forming apparatus is arranged on the image panel such that the black belt is disposed at the center of the panel. Further, Japanese Patent Laid-Open No. 2006-79097 describes that the three-dimensional image forming apparatus can be disposed on the image panel without positional deviation by displaying different images on the two pixel arrays.
Japanese Patent Laid-Open No. 2008-015394 proposes a method of manufacturing a stereoscopic image display apparatus that forms an image for alignment on a synthesized image synthesized from original images for different viewpoints and for at least one of the top and bottom of the synthesized image, and that aligns the synthesized image and optical means with each other from a position nearer the synthesized image than the position from which the stereoscopic image is viewed on the basis of information of the image for alignment observed via the optical means for extracting a prescribed viewpoint image.
FIG. 3 is a schematic diagram showing an image for alignment described in Japanese Patent Laid-Open No. 2008-015394.
FIG. 3 illustrates a manner where images for alignment are disposed at the top and bottom of synthesized image 102, in which original images for three viewpoints are divided along the vertical direction and disposed. The images for alignment have different colors corresponding to the original images for different viewpoints.
When the images for alignment are viewed from a point nearer the synthesized image than the view point of the stereoscopic image via optical means, it is observed as a striped pattern in which different colors are disposed. In Japanese Patent Laid-Open No. 2008-015394, the colors and positions of the striped pattern are read and thereby it is determined the viewpoint image which is disposed at a position capable of being viewed from the front viewpoint. Further, the patterns of the images for alignment disposed at the top and bottom are matched with each other and thereby a relative slope between the synthesized image synthesized from the images for the different viewpoints and the optical means.
Japanese Patent Laid-Open No. 2009-162620 proposes an inspection apparatus for inspecting relative positional deviations of elements and accuracies of parts of a three-dimensional image reproduction apparatus.
FIG. 4 is a block diagram showing a configuration of the inspection apparatus described in Japanese Patent Laid-Open No. 2009-162620.
The inspection apparatus shown in FIG. 4 includes: three-dimensional image reproduction apparatus 500 including an optical element, such as pinhole array 509 (or lenticular sheet 512) and an aperture slit, and liquid crystal display 501; signal processing device 422 for causing three-dimensional image reproduction apparatus 500 to display a prescribed test pattern; photographing optical system 412 photographing the test pattern displayed on three-dimensional image reproduction apparatus 500; and analysis device 513 analyzing the taken inspection image.
Inspection apparatus shown in FIG. 4 causes liquid crystal display 501, where pixels are two-dimensionally arranged, to display the test pattern for switching on the pixels on a desired cycle, photographs the test pattern as an inspection image, analyzes the inspection image and thereby detects the relative positional deviation of the elements of the three-dimensional image reproduction apparatus. For instance, if the pixels are switched on at the positions of valleys of lenticular sheet 512 at a pitch of pixels substantially identical to the pitches of lenticular sheet 512, distribution of angles of edges capable of being displayed by respective lenses can be measured as image width W. The image with width W causes a positional deviation, if there is a relative positional deviation between lenticular sheet 512 and liquid crystal display 501. Accordingly, the amount of relative positional deviations of respective elements of the three-dimensional image reproduction apparatus can be detected by determining whether the amount of positional deviation of this image is within a prescribed reference value or not.
Japanese Patent Laid-Open No. 2009-223193 proposes a method for manufacturing a three-dimensional image display apparatus that photographs a position detection mark of a display panel and a lenticular lens and then detects relative positions of the display panel and the lenticular lens from the taken image.
FIG. 5 is a plan view showing an example of the taken image illustrated in Japanese Patent Laid-Open No. 2009-223193.
In Japanese Patent Laid-Open No. 2009-223193, position detection mark M1, such as an alignment mark, is provided at a peripheral region of the display panel so as enclose a display region, and a photographing region is set in region R1 including position detection mark M1 and an edge of lenticular lens 124a. FIG. 5 shows taken image G1 at this time. Art described in Japanese Patent Laid-Open No. 2009-223193 detects valley b1 of lenticular lens 124a from taken image G1, calculates deviation amount a1 in the x axis between position detection mark M1 and valley b1 and thereby detects relative positions of the display panel and the lenticular lens.
Japanese Patent Laid-Open No. 2010-019987 proposes an inspection apparatus for inspecting a three-dimensional image display apparatus, in which a display panel and a lenticular lens are fixed to each other, using an image for inspection.
FIG. 6 is a plan view showing an example of an image for inspection described in Japanese Patent Laid-Open No. 2010-019987.
In Japanese Patent Laid-Open No. 2010-019987, pixels disposed at the center of lens pitch P for each lens pitch P of the lenticular lens are switched on in a line, and an image including two position detection marks M1 and M2 on a line orthogonal to a pixel array is used as image for inspection G1. Image for inspection G1 is displayed on a display apparatus, inspection regions (e.g., 3×3=9 points) to be inspected are photographed, luminance distributions are acquired from the respective taken images, and thereby the deviation amount in a horizontal direction is detected.
Japanese Patent Laid-Open No. 2009-300816 proposes a manufacturing method and manufacturing apparatus that correctly align a display panel of a display apparatus providing different images in observation regions with a light travel controller.
FIG. 7 is a schematic diagram showing a manufacturing apparatus illustrated in Japanese Patent Laid-Open No. 2009-300816.
The manufacturing apparatus shown in FIG. 7 includes a display apparatus for displaying different images in eight observation regions Ob, and cameras 240a and 240b disposed in prescribed observation regions Ob. In Japanese Patent Laid-Open No. 2009-300816, the display apparatus and cameras 240a and 240b are arranged as shown in FIG. 7, and the light travel controller is aligned with respect to the display panel so as to reduce the difference between images actually taken by cameras 240a and 240b disposed in the prescribed observation regions and images to be taken by these cameras, thereby bringing an image to be viewed by an actual observer close to the optimal image.
However, the aforementioned related arts have problems described as follows.
The art described in Japanese Patent Laid-Open No. 2007-65441 only describes a method for deriving arrangement lens specifications. Even with adjustment of an angle of the parallel line group, separation adjustment, and adjustment of the horizontal reference position, this art is incapable of preventing the reverse view phenomenon in which right and left images at respective viewpoints are replaced with each other. Further, since a drawing process of the parallel line group and a controller used for adjustment thereof are required, the cost of the inspection apparatus is increased and operation time is also increased.
The art described in Japanese Patent Laid-Open No. 2006-79097 adjusts the black band, which is formed between image windows for right and left eyes, to a prescribed position. For instance, it is adjusted such that the black band is disposed at the center of the panel. However, even if the position of the black band is disposed at the center of the panel, it is also determined that there is no positional deviation if the three-dimensional image forming apparatus (optical means) is relatively inclined with respect to the image panel. That is, the art described in Japanese Patent Laid-Open No. 2006-79097 is incapable of detecting a relative slope between the image panel and the three-dimensional image forming apparatus (optical means). Further, the art described in Japanese Patent Laid-Open No. 2006-79097 has at least three view points and, in a case of inspecting an image panel whose number of viewpoints is odd, is incapable of displaying an image different in bilateral symmetricalness with respect to the displayed center. Accordingly, there is a problem that this art is incapable of inspecting this image panel.
According to the art described in Japanese Patent Laid-Open No. 2008-015394, the top and bottom parts of the synthesized image for arranging the alignment image are out of the display region. Even if there is an abnormality in the stereoscopic view formed by the synthesized image, the art cannot perform inspection. There is another problem in that, only with the colors and arrangement of stripes, the relative position between the alignment image and the lenticular lens can only be inspected one viewpoint at a time. There is still another problem in that a process of cutting the part where the alignment image is disposed is separately required. This increases the manufacturing cost and manufacturing time.
According to the art described in Japanese Patent Laid-Open No. 2009-162620, in a case where the number of viewpoints is two, with the test pattern switching on the column disposed in the valley of a lens pitch, the entire screen of the display apparatus is switched on. Accordingly, there is a problem in that the relative positional deviation of the display panel and the optical means cannot be read and inspection cannot be performed.
The art described in Japanese Patent Laid-Open No. 2009-223193 reads physical positions of the position detection mark of the display panel and the lenticular lens as they are, and detects the positional accuracy. Accordingly, in order to secure a required accuracy, high performance photographing means is required. Further, it is difficult to image the display panel and the lenticular lens at the same focus. Accordingly, there is a problem in that a certain amount of inspection time and expensive apparatus are required. Further, only local information at and around the mark is acquired. Accordingly, it is difficult to acquire information of the entire screen. For instance, in a case where the lenticular lens at a non-photographing part has an average distortion, detection is not easy.
The art described in Japanese Patent Laid-Open No. 2010-019987 is a method of inspection on each lens pitch P. In order to acquire information of the entire screen, inspection regions are required. Further, there is a problem in that, since the luminance distribution of the taken image of each inspection region is calculated, a certain amount of inspection time is required.
The art described in Japanese Patent Laid-Open No. 2009-300816 aligns the light travel controller with the display panel on the basis of images corresponding to respective observation regions. Accordingly, this art requires cameras for photographing an image of at least two of observation regions, or a special camera for photographing an image of the observation regions at one time. This increases the cost of the manufacturing apparatus.